Late last year our Samsung split system aircon stopped working. Having some electronics experience and many Big Clive videos under my belt, my first suspicion was the power supply in one of the three indoor units. In the end, I was correct, but an awful lot of mucking about was required to get it fixed!
During operation, this unit would occasionally stop, then beep (in the same way it does after power is interrupted/restored at the breaker), initialise, and could then be turned on again.
Over a few weeks this degraded to the point where the unit would reset several times while initialising, and then to the point where it couldn’t even stay on long enough to get through the beep, instead just constantly clicking. Definitely a symptom with the vibe of a failing capacitor or other component in the switch mode bootstrap circuit.
Unfortunately as the three indoor heads share the same outdoor unit, all three must be online for any of them to work. This manifests as the other units failing to initialise and flashing the timer and turbo lights (Communication Error). It would’ve been nice if the system could tolerate a failed indoor unit, but I don’t know enough about the refrigeration side to know if that’s feasible.
Sometimes if the breaker was left off for several days, the failed unit would be able to initialise and we could use the other two for a few days until it died again. Clearly a proper fix was needed.
After removing the main circuit board and not seeing any obvious issues, the first stop was looking for a replacement board online. If I had the time and tools, I probably could’ve narrowed down the problem and fixed it without a wholesale replacement, but given AliExpress had a replacement at a reasonable price, that’s what I went with.
And that could’ve been the end of the story, were it not for something buried on page 412 of a Samsung service manual, but I’ll come back to that.
I had expected the new board may need some configuration, and I found information about this in the manual for the range of indoor units. It looked like the only thing I’d need to change was the indoor unit address to make sure it didn’t conflict with one of the others.
When the board arrived, I got it all plugged in, turned the power on, and all three lights on the unit started blinking, meaning “EEPROM Option Error”. That seemed reasonable, however no amount of address setting, making sure all units had a unique address, or poking some of the other options seemed to get it working.
As the new board had arrived wrapped in foam, and I couldn’t find any more information about this error state, I ended up assuming it must’ve been killed by static on the journey, or perhaps it was broken right from the beginning. I decided to see if swapping a few of the power supply parts onto the existing board might be enough to revive it. With just solder braid, and no oscilloscope, ESR meter, or safe way to power the board outside of the AC unit, it’s safe to say this was an absolute pain in the ass, especially given it didn’t make any obvious improvement to the issue.
So we called in an AC company. I’ll save my rant about repairability, but it did take some convincing to get them to consider repairing it instead of just wholesale replacing the system, which would’ve been Very Fun™ in an apartment with next to no ceiling void access.
It then took more convincing that the problem was in the indoor unit, and in the end they replaced the indoor unit board, as well as the VFD board for the compressor motor. Don’t ask me why, because I don’t know either.
BUT, after they were done with that the indoor unit was still blinking for “EEPROM Option Error”. After much more scouring of the Internet, I came across this video from Samsung, which mentions “Product option” codes as starting with 01. The manual from earlier only documented codes starting 0A, 02, 05 and 0D, so it seemed like this could be it.
This eventually led me to a Samsung Service Manual, which lists a bunch of these 01 codes under the cryptic heading “Option Items”.
Going down the list revealed our indoor unit model (AM028KNQDEH/EU) should have the code 010044-1160C8-201C1C-310000, which due to the inane way these codes are entered, means entering 10-04-41-60-C8-01-C1-C1-00-00 through the process described in the original manual.
And that fixed it! In the end, it makes sense that the board needs to be told what exact product it’s installed in, and it also makes some degree of sense why this wasn’t in the indoor unit manual, as in that case the board would’ve come with the unit and would presumably have the correct code set at the factory.
It would just be nice if this information was more accessible, maybe manufacturers could even sell spare parts directly, complete with instructions, what a thought!
Comments